1. Field of the Invention
The present invention relates to an apparatus for applying air pressure to one end of a filter cigarette, as a rod-shaped article, in order to check the filter cigarette for dilution.
2. Description of the Related Art
A filter cigarette is composed of a cigarette and a filter which is connected to one end of the cigarette by means of a paper piece wound thereon. In filter cigarettes of some kinds, the paper piece or paper ring is formed having a plurality of pores. When a filter cigarette of this type is smoked, smoke inhaled by a smoker is diluted by air introduced through cigarette paper and pores therein. Since this introduction of air lowers the temperature of the smoke, nicotine and tar in the smoke are reduced in quantity, so that the smoker can enjoy light taste of smoke.
Unless the quantity of air introduced through the pores in the individual filter cigarettes and the cigarette paper, that is, the dilution of the smoke, with regards to the manufacture of the filter cigarettes of this type, is constant, therefore, the taste is unstable, and the quality of the filter cigarettes lacks in uniformity.
Accordingly, an inspection device for checking the individual filter cigarettes for dilution is incorporated in a filter cigarette manufacturing system. An example of this inspection device is described in Published Unexamined Japanese Patent Application No. 3-172936.
This conventional inspection device comprises an inspection drum, which constitutes part of a transportation path for filter cigarettes. More specifically, the inspection drum has a number of suction grooves on the outer peripheral surface thereof, the suction grooves serving to attract and transport the filter cigarettes as the inspection drum rotates.
Further, a pair of pads for each suction groove is arranged on the outer peripheral surface of the inspection drum. These pads, which are located on either side of the suction groove, move toward and away from each other as the inspection drum rotates. When a filter cigarette in the suction groove reaches a predetermined rotational angle zone, with respect to the rotating direction of the inspection drum, as the drum rotates, therefore, the paired pads corresponding to the suction groove are pressed individually against the opposite ends of the filter cigarette, thereby holding the filter cigarette between them.
An air pressure is applied to one end or the cigarette-side end of the filter cigarette through one pad, while an air pressure appearing at the other end or the filter-side end of the filter cigarette is outputted through the other pad. When the difference between the air pressures at the opposite ends of the filter cigarette, that is, the differential pressure between the input and output air pressures, is measured, the dilution of the filter cigarette can be detected by the differential pressure.
Since the dilution of the filter cigarette is detected on the basis of the aforesaid differential pressure, the input air pressure applied to the filter cigarette and the output air pressure delivered therefrom should be measured accurately. To attain this, the paired pads must be fully in intimate contact with the opposite ends of the filter cigarette during the inspection of the filter cigarette dilution. If there are gaps between the pads and the end faces of the filter cigarette, the measured input or output air pressure cannot represent an accurate value, so that the dilution, obtained according to the differential pressure between the input and output air pressures, is inaccurate.
However, each end face of the filter cigarette, especially the cigarette-side end face, is neither flat nor precisely round. Further, the cigarette-side end face is not necessarily perpendicular to the axis of the filter cigarette.
Even though the one pad is pressed against the cigarette-side end face, therefore, it is difficult to bring the pad and the cigarette-side end face into intimate contact with each other, and a gap may possibly be formed between them. As mentioned before, this gap lowers the reliability of the detection of the dilution of the filter cigarette.
If the rotating speed of the inspection drum increases with the increase of the operating speed of the manufacturing system, the time required for the filter cigarette to pass the rotational angle zone, that is, the period of time during which the paired pads are in intimate contact with the filter cigarette, becomes shorter. Thus, air leaking from the gap between the pad and the cigarette-side end face of the filter cigarette exerts a substantial bad influence upon the detection of the dilution.